Humans are playing a very long game with earth's climate

Effects of carbon emissions could last 10,000 years, study finds

The effects of burning fossil fuels today could persist for 10,000 years, according to a new study that takes the long view on the consequences of climate change

The Christian Science Monitor, Feb. 8, 2016

If humans don’t cut carbon emissions soon, the Earth could feel the catastrophic impact for tens of thousands of years, a new study has found.

In a shift from climate change analyses that focus on the phenomenon’s effects in the 21st century, researchers from an array of universities in the United States and Europe took the long view in their new study, released online Monday in the journal, Nature Climate Change. The findings suggest that the consequences of fossil fuels burned today could last well beyond 2100 – and the study is meant to urge policymakers to act with that perspective in mind.

“Much of the carbon we are putting in the air from burning fossil fuels will stay there for thousands of years – and some of it will be there for more than 100,000 years,” said Peter Clark, an Oregon State University paleoclimatologist and lead author on the article, in a statement,. “People need to understand that the effects of climate change on the planet won’t go away, at least not for thousands of generations.”

Most climate change policy debate is based on examinations of the past 150 years and their impact on rising sea levels and global warming by the end of this century, the researchers said.

But climate has a long memory, and focusing on a specific geologic period creates a false perception “that human-caused climate change is a twenty-first-century problem, and that post-2100 changes are of secondary importance, or may be reversed with emissions reductions at that time,” said Thomas Stocker, a climate scientist at the University of Bern and a co-author on the report, to Gizmodo.

Using new data over the last 20,000 years on the ties among carbon dioxide, temperature, and sea levels, the scientists projected what the impact of climate change on Earth would look like over the next 10,000 years.

They looked at the impact of four possible levels of carbon pollution – ranging from 1,280 to 5,120 billion metric tons – emitted into the atmosphere from the year 2000 to 2300. Since 1750, humans have released about 580 billion metric tons of carbon dioxide into the atmosphere, say the researchers.

In each level, carbon emissions fell to zero by 2300, but the impact of the damage persisted another ten millenia. In the high-emissions scenario, for instance, global temperatures peak at 7 degrees Celsius in 2300, but drop by just one degree over the next 10,000 years. Even the low-emissions scenario saw sea levels rise by up to 25 meters, directly affecting 10 percent of the population of more than 120 countries, Professor Clark said.

“We can’t keep building seawalls that are 25 meters high,” he said. “Entire populations of cities will eventually have to move.”

Over the long run, the authors say, climate change may well be the greatest threat to humanity’s survival – and it’s high time policymakers saw it that way and acted accordingly.

“Taking the first steps is important, but it is essential to see these as the start of a path toward total decarbonization,” said Daniel Schrag, a professor of geology at Harvard University who also worked on the study, in a statement. “This means continuing to invest in innovation that can someday replace fossil fuels altogether. Partial reductions are not going to do the job.”